A known form of spring interior comprises a plurality of longitudinally extending bands of springs disposed side by side and connected together by helical wires which extend transversely of the bands and embrace portions of the bands. Several kinds of bands of springs have been proposed for incorporation in spring interiors. One kind of band, which is the subject of British Patent No. 1,104,884, will hereinafter be referred to as a band of interlocked or interlaced springs. It comprises a single length of spring wire shaped to form a plurality of individual coil springs arranged in a row, one end turn of each coil spring lying adjacent to a top face of the band and the other end turn of each coil spring lying adjacent to a bottom face of the band, each coil spring being of a rotational hand opposite to the rotation hand of the adjacent coils immediately before and after it in the row, and being joined to the adjacent coil springs by a pair of interconnecting segments of wire integral with the coil springs. One of the pair of interconnecting segments is located in the bottom face of the band, and the other of the pair of interconnecting segments is located in the top face of the band. Each interconnecting segment comprises a bridging portion between adjacent coils, which bridging portion extends generally lengthwise of the row, and end sections connecting the bridging portion to the adjacent coils, which end sections extend generally transversely of the rows.
When bands of interlocked springs of the type described hereinabove are assembled to form a spring interior, they are disposed side by side and interconnected by helical lacing wires, some of which lie in the top face of the spring interior and others of which lie in the bottom face thereof, the top and bottom faces of the spring interior being the faces defined by the top and bottom faces of the bands incorporated in the spring interior. Each helical wire extends across the bands of springs and embraces portions of wires of the bands that extend transversely of the bands from the ends of the bridging portions of the links. In the top face of the spring interior the helical wires are disposed at uniform intervals along the bands of springs, the arrangement being such that there are two springs disposed in the interval between each helical wire and the next. There is a similar arrangement in the bottom face of the spring interior.
In this description of the invention there are references to faces of bands of springs and of spring interiors. As the bands of springs and spring interiors are, of course, of open-work or skeletal form, the term "face" must be understood as referring to an imaginary surface defined by the relevant parts of the bands or spring interiors. Furthermore, as the wires and helical wires are of finite width or thickness and as they sometimes overlap each other, the term "face" cannot be understood as having a strictly geometrical meaning. Nevertheless, as the faces concerned are relatively extensive and are of flat shape, their locations can in practice be determined without difficulty or ambiguity.
It is customary for a bedding spring interior to be incorporated in an upholstered article. In such an article at least one of the main faces of the spring interior (that is the top and bottom faces thereof) is covered by a layer or layers of padding. This in turn is covered by a cover made of sheet material, such as ticking or upholstery fabric.
A primary cost of producing a bedding spring interior is the cost of the wire used to create the bands of springs and their requisite connecting and supporting structures. Therefore, it can generally be said that by reducing the quantity of wire used in the bedding spring structure, one will reduce the cost of producing such a structure. Furthermore, reduction in the production cost of a bedding spring interior will be realized if one can speed up the production process and simplify the manufacturing machinery required to produce the spring interior.
It has therefore been an objective of this invention to provide an improved bedding spring interior made from bands of interlocked springs which reduces the amount of wire needed per unit and at the same time reduces the amount of time required to produce the unit but without sacrificing firmness or durability of the unit.
Still another objective of this invention has been to provide an improved spring interior made from bands of interlocked coils which facilitates production without requiring more complicated machinery and, in fact, which may be made on less complicated and expensive machinery than is currently used in existing production lines.